Air in the brake system can make your brake pedal feel spongy and vague. You should flush the fluid every two or three years, which is a relatively easy two-person project.

Semis and similarly sized vehicles, like buses, have air brakes, and that sound is made by the safety valves resetting the ...

Your pedal probably feels spongy and it’s often hard to feel exactly when the brakes start to bite. These are the telltale signs of air in the braking system, which happens over time with use.